I have a 1990 RE4F02A trans.
120,000 easy miles.
Trans was starting to slip in 3ed and 4th.
I saw on the Trans-go web site that the kit could be installed without the trans coming out.
Got the kit and found it to be un-true. Kind of.
Kit comes with springs, *****, seal rings.
NOTE: No gaskets in the kit. You'll need 5 gaskets to install the whole kit. 4 for the valve body itself.
I decided to install just the parts that didn't requier the trans to be removed.
Only the valve body. One spring and drill one hole.

Results are good.
Slipping went away. Under normal driving.
Over all it feels better. So it did help.

To install the rest of the kit, the trans needs to come out.
If I'm going to pull the trans, I'll just replace the clutches also.
Doesn't make sense to not do it at the same time.

Was the kit worth it????
Maybe.
I should have tested the spring to find the compression rate. I didn't. If I did I could just look for a spring.
I know which hole to enlarge from the instructions.
That's all I would have needed.
Probably would have saved $38.00.